Quasinormal Modes of Modified Gravity (MOG) Black Holes

TL;DR

This paper calculates quasinormal modes of black holes in Modified Gravity (MOG), revealing how these modes differ from standard GR black holes and their potential observability in gravitational wave signals.

Contribution

It provides the first detailed analysis of gravitational and electromagnetic QNMs in MOG black holes, highlighting the effects of the model parameter on mode frequencies.

Findings

Both real and imaginary parts of QNMs decrease with increasing alpha.

Mass re-scaling causes Im(omega) to match GR, while Re(omega) is higher.

Results are relevant for gravitational wave observations of black hole mergers.

Abstract

The Quasinormal modes (QNMs) for gravitational and electromagnetic perturbations are calculated in a Scalar-Tensor-Vector (Modified Gravity) spacetime, which was initially proposed to obtain correct dynamics of galaxies and galaxy clusters without the need for dark matter. It is found that for the increasing model parameter $\alpha$, both the real and imaginary parts of the QNMs decrease compared to those for a standard Schwarzschild black hole. On the other hand, when taking into account the $1/(1+\alpha)$ mass re-scaling factor present in MOG, Im($\omega$) matches almost identically that of GR, while Re($\omega$) is higher. These results can be identified in the ringdown phase of massive compact object mergers, and are thus timely in light of the recent gravitational wave detections by LIGO.